Windshield wiper system with blade assembly drive for maintaining a constant attack angle of the wiper blade on a curved a windshield

ABSTRACT

A windshield wiper system for vehicles with a windshield having a curved surface with a curvature across the width of the vehicle is disclosed. The system comprises at least one driven wiper arm. A wiper blade assembly is mounted on a free end of the wiper arm. The wiper blade assembly defines a longitudinal axis and it is mounted pivotally about an axis parallel to the longitudinal axis. An oscillating drive oscillating the wiper arm across the windshield. A pivot drive is connected to said wiper blade assembly and it is adapted for driving the wiper blade assembly in accordance with an oscillatory movement of said wiper arm. The pivot drive includes a cam follower for pivoting the wiper blade assembly relative to said wiper arm and for maintaining a substantially constant attack angle of the wiper blade assembly relative to the windshield surface during the oscillatory movement of the wiper arm. The cam surface on which the cam follower rides may be defined by the surface of the windshield or by a separately provided cam member.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 08/039,808, filedMar. 30, 1993, now U.S. Pat. No. 5,384,432; which was a Continuation ofInternational Application PCT/AT91/00103, filed Sep. 20, 1991.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a windshield wiper system for vehicles with awindshield which is curved transversely, i.e. it is curved across itswidth. The system is provided with at least one driven wiper arm onwhose free end a wiper blade is mounted. The wiper blade is caused topivot about a longitudinal axis parallel to the wiper blade. A pivotdrive for the wiper blade is derived from the wiper arm movement.

Particularly passenger vehicles have windshields with an arch acrosstheir width. The arch usually becomes steeper at the lateral regions. Awiper arm which only oscillates across the arched window therefore onlyhas one position in which the wiper blade lies vertically on the window,while all other positions within the wiping area result in a deviationfrom the 90° position. That deviation from the vertical, also called thenormal error, influences the wiping quality, the reorientationcharacteristic of the wiper rubber in the reversal points and theaerodynamic properties of the wiper system.

2. Description of the Related Art

It has been attempted, therefore, to provide windshield wiper systems inwhich the wiper blade is pivoted in addition to the oscillatory motion.A windshield wiper of the above-mentioned type has become known fromEP-A 351 528, for example, in which pivoting of the wiper blade on thewiper arm in dependence on the oscillation angle of the wiper arm iscaused by a bendable shaft which is fixed at one end. While this leadsto a change in the attack angle of the wiper blade, it does not considerthe windshield curvature, however. The attack angle will remainapproximately constant in this only in those special instances in whichthe windshield curvature follows the pivoting of the wiper blade on thewiper arm. This is generally not the case in the lateral edge regions,however, as can be seen in FIG. 2 of EP-A 351 528.

U.S. Pat. Nos. 3,006,788 and 2,979,425 show structures in which thewiper arm is formed of two parts and the part carrying the wiper bladeis pivotable in a second part by means of a rod assembly which isslidable in a non-linear slaving guide.

In the windshield wiper according to U.S. Pat. No. 4,858,268, a pivotingof the wiper arm takes place in dependence on its oscillation about atransverse axis. Only a curvature of the windshield in a direction ofthe transverse axis is considered.

Finally, windshield wipers are known from EP-A 21 914 and 330 663, whosewiper arm or the wiper arm part carrying the wiper blade are pivotedabout its longitudinal axis, whereby a control cam and a cam followerelement are provided in the region of the wiper arm oscillation bearing.These two embodiments are able to keep the normal error at least small,as long as the wiper blade extends approximately parallel to the wiperarm. In reality, however, this parallelism is given only with fewwindshield wipers, since substantial angles are present between thewiper blade and the wiper arm in the parking position and for a bestpossible coverage of the driver's viewing field. Such configurations areparticularly unsuited for windshield wiper systems, the wiper blade ofwhich is guided across the windshield substantially parallel and whichare rotated relative to the wiper arm for that purpose.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a windshieldwiper system, which overcomes the hereinaforementioned disadvantages ofthe heretofore-known devices of this general type and which makes itpossible, independently of the type of system, to keep the normal errorat least within acceptable limits or, preferably, to avoid the samealtogether.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a windshield wiper system for vehicleswith a windshield having a curved surface, comprising: at least onedriven wiper arm having a free end; a wiper blade assembly mounted onthe free end of the wiper arm, the wiper blade assembly defining alongitudinal axis and being pivotally mounted about an axis parallel tothe longitudinal axis; an oscillating drive for oscillating the wiperarm across the windshield; and a pivot drive connected to the wiperblade assembly and being adapted for driving the wiper blade assembly inaccordance with an oscillatory movement of the wiper arm; the pivotdrive including cam follower means for pivoting the wiper blade assemblyrelative to the wiper arm and for maintaining a substantially constantangle of the wiper blade assembly relative to the windshield during theoscillatory movement of the wiper arm.

In other words, the objects of the invention are solved in that theoscillating drive of the wiper blade includes a not-pivotally mountedcontrol cam and a cam follower which is guided along the control camduring the oscillatory motion of the wiper arm and which is disposed onthe wiper blade.

A configuration is thus attained which, independently of the position ofthe wiper arm, does not alter the orientation of the curvature axesdetermining the control cam relative to the vehicle. The pivot axiswhich usually extends at the free end vertically to the wiper blade,thereby lies in front of or behind, or above or below the additionalpivot axis according to the invention, so that a kind of universal jointis formed between the wiper arm and the wiper blade. It is also possiblethat the two pivot axes intersect.

In accordance with an added feature of the invention, the cam followermeans are formed of at least one support roller disposed laterally ofthe wiper blade assembly and rotatable about an axis substantiallyparallel to the wiper blade assembly, the support roller following thesurface of the windshield during the oscillatory movement of the wiperarm. This is a structurally particularly simple embodiment, as itprovides for the control cam to be formed by the arched windshielditself and that the cam follower is provided in the form of supportrollers rolling on the windshield, which rollers are disposed laterallyof the wiper blade. The support rollers which, in particular, aremounted on spring arms or dump irons attached to the wiper blade, followthe curvature of the windshield. This assures the pivoting of the wiperblade during the oscillatory motion of the wiper arm and thus themaintaining of the vertical attack angle.

In accordance with an additional feature of the invention, the at leastone support roller are two support rollers disposed mutually oppositeone another across the wiper blade assembly.

In accordance with a further feature of the invention, the windshieldwiper system includes a springy arm resiliently connecting the at leastone support roller to the wiper blade assembly.

In accordance with yet an added feature of the invention, cam means aredisposed on the free end of the wiper arm, the cam means being formed ofa plate having a cam surface, and the cam follower riding on the camsurface.

It is thus a second embodiment in which the control cam may be movedtogether with the wiper arm when the two pivot drives are mechanicallycoupled. A preferred embodiment provides that the control cam is formedon a plate mounted on the free end of the wiper arm.

Depending on the construction of the windshield wiper system, twopreferred embodiments result. In the first embodiment, the plate ismounted at the free end of the wiper arm and it is rotatable about anaxis parallel to the wiper arm oscillation axis and it is non-rotatably,i.e. linearly guided during the wiper arm oscillatory motion. Thisembodiment is particularly suited for windshield wiper systems in whichthe wiper blade maintains its position relative to the wiper arm duringthe wiper arm oscillation, i.e. the wiper blade swings with the wiperarm.

In accordance with yet an additional feature of the invention, thewindshield wiper system includes a shaft disposed on the free end of thewiper arm, the plate being pivotally mounted on the shaft, the wiper armoscillating about an oscillatory axis during the oscillatory motion andthe shaft extending parallel to the oscillatory axis, and includingmeans for maintaining the plate at a substantially constant orientationangle relative to the windshield during the oscillatory motion of thewiper arm.

In accordance with yet a further feature of the invention, the plate isnon-rotatably mounted on the shaft, the wiper arm oscillates about anoscillatory axis during the oscillatory motion and the shaft extendsparallel to the oscillatory axis, and including means for rotating thewiper blade assembly about the shaft during the oscillatory motion ofthe wiper arm.

In accordance with again an added feature of the invention, the pivotdrive further includes parallel guide means operatively connected to theplate for guiding the plate. In a preferred embodiment, the parallelguide means include a parallelogram control lever articulated at a pivotpoint being stationary with respect to the motor vehicle.

In accordance with again an additional feature of the invention, thesystem including means for altering a length of the wiper arm during theoscillatory motion, the means being in the form of a control drive and,in a preferred embodiment, the parallel guide is formed by a part of thecontrol drive.

With the objects of the invention in view, there is further provided, inaccordance with the invention, a windshield wiper system for vehicleswith a windshield having a curved surface, comprising: at least onedriven wiper arm oscillating about an oscillatory axis being stationaryrelative to the vehicle, the wiper arm having a free end opposite theoscillatory axis; a bearing member disposed at the free end and beingrotatable about a bearing member axis parallel to the oscillatory axis;a wiper blade assembly mounted on the bearing member; oscillatory drivemeans for oscillating the wiper arm; pivot means for pivoting the wiperblade assembly about an axis parallel to the wiper blade assembly, thepivot means including a cam having a cam surface and a cam followerfollowing the cam surface during a rotation of the wiper blade assemblyrelative to the wiper arm, the pivot means defining an attack angle ofthe wiper blade assembly relative to the surface of the windshield.

In accordance with a concomitant feature of the invention, the systemincludes means for rotating the wiper blade assembly relative to thewiper arm having a parallel guide translating an oscillatory motion ofthe wiper arm into a rotating motion of the wiper blade assemblyrelative to the wiper arm.

The second preferred embodiment provides for the plate to benon-rotatably mounted on the free end of the wiper arm and for the wiperblade to be rotatable in the wiper arm about an axis parallel to thewiper arm oscillatory axis. In this embodiment of the wiper system, thewiper blade sweeps essentially the entire surface of the windshieldduring the pivoting motion of the wiper arm and it rotates relative tothe wiper arm. In other words, the blade sweeps the windshieldessentially horizontally, while maintaining a vertical orientation.

In both embodiments, a parallel guide for the wiper arm oscillatorydrive may be used for guiding the plate or the wiper arm. The parallelguide can, in the case of a rotatably mounted plate, be formed by aparallelogram lever which is articulated at a stationary point withrespect to the vehicle, or it can, in the case of a plate non-rotatablymounted on the wiper arm, be formed as a part of a control drive whichalters the length of the wiper arm and which is necessary for guidingthe wiper blade parallel to the lower windshield edge.

Instead of coupling with the pivot drive of the wiper arm, it is alsopossible to provide a separate control drive.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a windshield wiper system, it is nevertheless not intended to belimited to the details shown, since various modifications and structuralchanges may be made therein without departing from the spirit of theinvention and within the scope and range of equivalents of the claims.

The construction of the invention, however, together with additionalobjects and advantages thereof will be best understood from thefollowing description of the specific embodiment when read in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top-plan view of a windshield of a motor vehicle with afirst embodiment of the windshield wiper system according to theinvention;

FIG. 2 is a top-plan view of a windshield of a motor vehicle with asecond embodiment of the windshield wiper system;

FIG. 3 is a partial sectional view through the wiper arm in a firstembodiment;

FIG. 4 is a partial top-plan view of a second embodiment of the wiperblade mounting in a central operating position;

FIG. 5 is a sectional view similar to that of FIG. 3 of the embodimentof FIG. 4;

FIG. 6 is a partial top-plan view of the embodiment of FIG. 4 in anoperating position pivoted to the right-hand side;

FIG. 7 is a partial longitudinal section through a third embodiment ofthe wiper blade mounting;

FIG. 8 is a section along the line VIII--VIII of FIG. 7;

FIGS. 9 and 10 are partial sections of a central operating position andan operating position pivoted to the right-hand side, respectively, ofthe embodiment of FIG. 7;

FIG. 11 is a partial sectional view of a fourth embodiment;

FIG. 12 is a top-plan view of the embodiment of FIG. 11;

FIG. 13 is a view similar to FIG. 11 of a fifth embodiment;

FIG. 14 is a view similar to FIG. 12 of the embodiment of FIG. 13;

FIG. 15 is a partial sectional view of a sixth embodiment;

FIGS. 16 and 17 are partial sections of a central operating position andan operating position pivoted to the right-hand side, respectively, of aseventh embodiment; and

FIGS. 18-20 are views similar to those of FIGS. 7, 9 and 10 of an eighthembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first,particularly, to FIGS. 1 and 2 thereof, there is seen a motor vehicle 1with a windshield 2. The windshield 2 is curved transversely from oneside of the vehicle 1 to the other side, i.e. along its width. In thewindshield wiper systems according to the invention, the normal error,i.e. the deviation of the wiper blade from a vertical attack angle onthe vehicle windshield 2, is reduced or avoided. The windshield wipersystems can be embodied as single-arm or as double-arm wipers, wherebythe wiper blade of FIG. 1 may be rotated about a wiper arm oscillatoryaxis 8 or the wiper blade of FIG. 2 may be guided essentially parallelto the lower edge of the windshield 2. An oscillatory drive 3 with adrive motor 4 is installed in a known manner below the vehiclewindshield 2 on the vehicle 1, and a wiper arm 5 oscillates about thewiper arm oscillatory axis 8; several positions are illustrated in FIGS.1 and 2, respectively.

With reference to FIG. 3, a wiper blade assembly 6, in the followingalso referred as a wiper blade 6, is pivotable at the free end of thewiper arm 5 about a transverse axis 21 and about a longitudinal axis 9which extends parallel to the wiper blade 6, and, in the embodiment ofFIG. 1, extends substantially parallel to the wiper arm 5.

In the embodiment of FIG. 2 the blade 6 is additionally rotatable abouta shaft 17, which is oriented parallel to a wiper arm oscillatory axis8. The pivotability about the longitudinal axis 9, which is parallel tothe wiper blade 6, makes for the avoidance of the normal error, i.e. ithelps maintain a position of the wiper blade 6 with a wiper rubber 7which is vertical to the vehicle windshield, independently of thecurvature of the windshield 2 and its angle relative to the wiper arm 5and the wiper arm oscillatory axis 8.

Various possibilities are proposed by this inventor for maintaining orguiding the wiper blade 6 with an attack angle of about 90° relative tothe windshield 2. With reference to FIG. 3, for instance, there areprovided spring arms 10 or dump irons 10 laterally mounted on a supportmember 26 or bearing member 26 of the wiper blade 6. The wiper bladeassembly is pivotable about the longitudinal axis 9. Support rollers 11are mounted at the springy dump irons 10 on a level with the wiperrubber 7. The windshield 2 is used as a control cam and the rollers 11serve as cam followers 13. The support rollers 11 roll on the windshield2, i.e. the cam 12 during the oscillatory motion of the wiper arm 5, sothat the normal position of the wiper blade 6 is assured. Again, thewiper blade 6 is disposed centrally between the support rollers 11 andit lies on the windshield 2. The embodiment of FIG. 3 is particularlywell suited for windshield wiper systems according to FIG. 1 with eitherone or two wiper arms 5.

With reference to FIGS. 4-6, the second embodiment shown therein servesfor such windshield wiper systems in which the control cam 12 isprovided on a plate 16 or disk 16. The plate 16 is mounted on the freeend of the wiper arm 5, rotatably about a shaft 17, which is parallel tothe wiper arm oscillatory axis 8, and it is provided with a parallelguide 18. The parallel guide 18 comprises a parallelogram control lever19, which is articulated at an extension 23 of the plate 16. When thewiper arm 5 is rotated, as can be seen from a comparison between FIGS. 4and 6, the plate 16, and thus the control cam 12 disposed on the wiperarm at the lower end of the plate 16, is also pivoted. A cam follower 3provided on the mounting member 26 of the wiper blade 6 lies on thecontrol cam 12. The cam follower 13 comprises two laterally extendingfingers or rollers. The wiper blade 6, which is non-pivotally mounted onthe wiper arm 5, is thus pivoted when the wiper arm 6 pivots about thelongitudinal axis 9, so that the normal position of the wiper blade 6 isnearly assured, or when the control cam is adapted to the curvature ofthe windshield 2, it is exactly assured.

With reference to FIGS. 7-10, a wiper arm used in the windshield wipersystems according to FIG. 2, alters its length with the oscillatoryangle. This assures full-surface coverage of the windshield 2. A controldrive with a cable line drive, which is not described in detail in thiscontext, serves as the parallel guide 18 for the rotation of the wiperblade 6 about the shaft 17. The shaft 17 extends parallel to the wiperarm oscillatory axis 8 and it is mounted in the free end of the wiperarm 5. The control drive, which also causes the length change in thewiper arm 5, includes a drive worm 24 which is driven by the cable linedrive and which meshes with a worm gear 25 disposed on the shaft 17. Theplate 16 providing the control cam 12 is formed on the lower side of thewiper arm 5. Force-guided fingers or rollers provided on the mountingmember 26 of the wiper blade 6 serve as the cam follower 13. Theparallel guide 18 necessary for the pivoting of the wiper blade 6relative to the wiper arm 5 is thus also used for pivoting the wiperblade 6 about the longitudinal axis 9 (FIGS. 9, 10). An adaptation ofthe control cam 12 to the respective curvature of the windshield 2 leadsto an exact maintaining of the normal position of the wiper blade 6 inthis embodiment as well.

The embodiments according to FIGS. 11-14 show variations of aparallel-guided wiper blade 6 for windshield wiper systems according toFIG. 2. The difference of the embodiment of FIG. 11 and 12 with respectto the embodiment of FIGS. 4-6 lies in the fact that the plate 16carrying the control cam 2 is rigidly (non-pivotally) connected with thewiper arm 5, and that the parallelogram control lever 19 rotates thewiper blade 6 via a side bar 22. In FIGS. 13 and 14, the longitudinalaxis 9 of the wiper blade 6 is disposed in the side bar 22, whichconnects the wiper arm 5 with the parallelogram control lever 19 of theparallel guide 18. Here, the control cam 12 is provided on the wiper arm5 and/or on the parallelogram control lever 19 and it is followed by thecam follower 13 projecting from the wiper blade 6.

Since non-pivotable and pivotable parts are interchangeable in order toequip the windshield wiper systems of FIGS. 1 or 2 in accordance withthe invention, they are not specifically defined in the two embodimentsof FIGS. 15-17. The plate 16 may thus either be a rigid part of thewiper arm 5 or it may be mounted thereon rotatably about the shaft 17.

Correspondingly, a parallelogram guide connects to either the wiperblade 6, which is mounted pivotally about the shaft 17, or on therotatably mounted plate 16. In FIG. 15, the cam follower 13 followingthe cam 12 is formed by springy arms 15. This provides a resilientcross-over of the wiper blade 6 at the reversal points and alsosimultaneous dampening for the wiper blade 6. This reduces wiper noiseand so-called rattling of the wiper blade is avoided, which is alsoattained with the embodiment of FIG. 3 by means of the spring arms 10.In the embodiment of FIGS. 16 and 17, the longitudinal axis 9 is notformed by a mounting pin, but by a spring leaf 14, which is insertedinto the wiper blade 6 and into the shaft 17.

In FIGS. 18-20, which essentially correspond to FIGS. 7, 9 and 10, adrive worm 24 is driven through a control drive 20 with a cable line.The worm 24 meshes with a worm gear 25. In the gear 25, the longitudinalaxis 9 is provided in which the wiper blade 6 is supported. The camfollowers 13 protrude upwardly from the mounting part 26 of the wiperblade 6, into the inside of the worm gear 25. They glide along thecontrol cam 12, which is provided on the inside of the wiper arm 5 orits outer cover. This embodiment is characterized by a smaller height ascompared to FIGS. 7-10.

In all of the embodiments, the wiper blade 6, due to the pivot axes 9and 21, which are orthogonal relative to one another, has a universaljoint-like suspension, which makes it possible in cooperation with thecontrol cam 12 adapted to the windshield or the windshield itself tomaintain the attack angle of the wiper blade 6 on the windshield 2 atleast substantially constant during the entire wiper arm movement. Theangle between the wiper blade 6 and the wiper arm 5 is thereby of noconsequence.

I claim:
 1. Windshield wiper system for vehicles with a windshieldhaving a curved surface, comprising:at least one elongated wiper armmounted for oscillation about an oscillatory axis and having a free end;an elongated wiper blade assembly defining a longitudinal axis, saidwiper blade assembly being pivotally mounted on said free end of saidwiper arm about an axis parallel to said longitudinal axis; anoscillating drive for oscillating said wiper arm about said oscillatoryaxis across the windshield; a shaft disposed on said free end of saidwiper arm, said shaft defining a longitudinal shaft axis extendingparallel to said oscillatory axis, said wiper blade assembly beingcoupled to said shaft; and pivot drive means connected to said wiperblade assembly for driving said wiper blade assembly about said axisparallel to said longitudinal axis as a function of an oscillatoryposition of said wiper arm; said pivot drive means including a cam witha cam surface pivotally disposed on said shaft and cam follower meansdisposed on said wiper blade assembly, said cam surface riding on saidcam follower means for pivoting said wiper blade assembly about saidaxis parallel to said longitudinal axis relative to said wiper arm andfor maintaining a substantially constant attack angle of said wiperblade assembly relative to the windshield during the oscillatorymovement of said wiper arm.
 2. The windshield wiper system according toclaim 1, wherein said cam is formed of a plate.